تاثیرات بالقوه استفاده از زمین های کشاورزی در پوشش خاک در پاسخ به تولید زیست انرژی در کانادا

The introduction of a market for agricultural biomass to feed large-scale second generation bioenergy (cellulosic ethanol) or other bio-products has positive implications for food producers and bio-product industries but may impact soil quality. In order to assess the potential impact on Canada’s agricultural lands, we integrated land use and soil capability maps and land management information to introduce several scenarios of crop residue harvest rates and land use conversions. The implications for soil quality, as represented by soil cover, were assessed for each scenario. The results showed that average soil cover at the national scale would decrease by more than 1 day if 40% of annual crop residues (by mass) were harvested, but the negative impacts could be resolved by increased adoption of conservation tillage methods. Additional biomass could be produced by converting low quality agricultural land to perennial biomass crops, but this would result in increased intensity of food production on high quality land. The total area of high and low quality land within the agricultural region of Canada is roughly equal, and the amount of high quality land currently used for perennial crops is about the same as the amount of low quality land used for annual crops, and ‘balancing’ production with capability would result in a net increase in both food and biofuel feedstock, with little impact to soil quality. About 6.73 M ha of high quality land is covered by forest, shrub and grass, and conversion of this land to agricultural production would have a negative impact on soil quality. The study indicates considerable potential for production of both food and biofuel feedstock on Canada’s agricultural lands through careful land use planning. Our analysis using soil cover as an indicator of environmental sustainability also indicates that land use planning should be cautious to prevent soil degradation. Particularly, regional variability of land use and soil capability distribution requires region specific land use policy for sustainable biofuel feedstock production.